Can you run two rectifiers on one turbine?

[makenzie71]

My rectifiers are rated for 100 amps but damn they get warm at around 50 amps.  Is it possible to run two in parallel to kind of break up that load and keep the heat down?

[MagnetJuice]

It is a bad idea to parallel bridge rectifiers. Diodes have different forward bias even when they are the same rating. Because of that, there is a chance that one will conduct a greater amount of current than the other conducts and fail.

High temperatures is the killer. It is better to provide better cooling to dissipate the heat.

I have a set of 50 amp bridges and sometimes I push over 60 amps through them. They are mounted on a massive piece of aluminum and cooled by a powerful fan.



I used the aluminum case of a powerful Pioneer car amplifier for a heat sink. The amplifier didn’t work, it was given to me by a friend.

Ed

[clockmanFRA]

I always put the biggest heatsink i can get.

This one is just right!






Hugh Piggott design 12 footers/3.7m diameter 48v.

[OperaHouse]

Paralleling rectifiers is done out in industry. While they do not share equally, they do share some.  This lower current thru each one can lower the forward voltage. Your reliability may increase, but they will still create about the same amount of total heat

[SparWeb]

Paralleling rectifiers isn't too bad, so I wouldn't object. 
You can do a lot with heat sinks, as suggested above.  Another way to get a good heat-sink is to take them off of microprocessors inside desktop computers.  Most of them now include a fan and a big smooth pad perfect for the surface of a bridge rectifier.  Other equipment you can scrounge heat-sinks from are old stereo amplifiers and TV's.

[Bruce S]

I find the best heat sinks come from the older Pentium 4s these are massive and the Dells usually have a Copper heat-pipe on them which helps even further.
For pure Aluminum size the old solid state mini-fridges I find that have been discarded some really good sized 6"x6" ( 15mm X 15mm) or larger.

Hope this helps
Bruce

[kitestrings]

Mounting them so that the fins are vertical also helps.  I learned that here at Fieldlines, thank you.  ~ks

[richhagen]

I have paralleled diodes before with success.  While they may have a specific forward voltage drop, this voltage drop is not constant with changing current.  For this reason I have been able to get the currents to split between diodes rather reliably in the past.  I am sure there are rules for de-rating them for current when connected in parallel, but I have seen it on commercial products as well, so it must be acceptable within certain rules.  Rich

[OperaHouse]

Forward voltage increases with current. At the same time forward voltage also drops with temperature increase. I's a race. So, you don't necessarily want to operate your diodes stone cold.  What you want is to try and operate all the diodes at the same temperature on the same heatsink. Don't put one of them on the edge because it is convenient where there is already a hole there.